EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To restrain deterioration of an exhaust gas characteristic and cost increase by extending heat resistant longevity by preventing heat deterioration. SOLUTION: CO, H2, THC are supplied to an occluded material of an occluded type NOx catalyst 25, carbonate grows and it is stabilized by preventing heat deterioration of a three-dimensional catalyst 22 by practicing stoichi-feed- back control in the case when catalytic temperature of an occluded type NOx catalyst 25 becomes higher than specified temperature and making a standard air-fuel ratio slight rich by prohibiting the stoichi-feed-back control in the case when the catalytic temperature exceeds catalyst heat resistant temperature at the time of this stoichi-feed-back control.